The effects of boiled coffee, filtered coffee, and tea on serum lipoprotein lipids and apoproteins were compared in 42 middle-aged hypercholesterolemic subjects (21 men and 21 women). The subjects consumed the beverages, eight cups a day, in random order during successive 4-week periods with 2-week run-in intervals in a crossover design. The diet was kept unchanged. Statistically significant differences were found between the periods in serum total cholesterol (P less than .0001 ANOVA), LDL cholesterol (P less than .01), and apoprotein B (P less than .01) levels. All differences were due to significantly higher levels during boiled coffee as compared with filtered coffee and tea. No statistically significant differences were found between the filtered coffee and tea periods. There were no differences in serum VLDL cholesterol or triglyceride, HDL cholesterol, and apoprotein A-I concentrations between the periods. Consumption of boiled coffee thus increased the concentration of low density lipoprotein in the serum without affecting its lipid-protein composition. The effect seemed to be determined by the method of brewing.